Here is the full list of all 14 Within Skerry achievements.
Complete Within Skerry by achieving the third ending
Complete any ending of Within Skerry in 25 minutes or less
Complete Within Skerry by achieving the second ending
Locate the holy cross to help fend off evil
Get off the kitchen counter!
Unlock all vault spinners
Escape the enemy trying to capture you
Snap 15 photos of paranormal activities
Snap 10 photos of paranormal activities
Complete Within Skerry by achieving the first ending
Locate all notes
Unlock the little white marble vault
Captured by the enemy running after you
Collect all cassettes